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Omomyid writes "In the seminal science fiction book 'Dune,' Frank Herbert envisioned the Fremen collecting water from the air via moisture traps and dew collectors. Science Daily reprints a press release from the Fraunhofer Institute in Stuttgart, where scientists working with colleagues from Logos Innovationen have developed a closed-loop and self-sustaining method, no external power required, for teasing the humidity out of desert air and into potable water."

Practically speaking, I doubt these traps could extract enough moisture from the air to have any effect on the humidity more than a few meters from the device. Even in huge numbers, the amount of air that comes in contact with one is negligible compared to the volume of air over the desert (the devices are on a roughly 2D plane, the atmosphere is 3D). Since the water would likely be used in the immediate vicinity (this doesn't look efficient enough to actually allow the export of water), whether it is used for crops or people, it will be added back into the local water cycle soon enough. At worst it will create minor, artificial oases. Remember, this air eventually passes over bodies of water which are more than capable of replenishing any moisture lost.

From a quick googling it seems that the reason that water tanks are illegal in the above states is not to do with affecting the local environment but more to do with the fact that it 'deprives' downstream users of their share.

I get the feel from the articles that downstream providers are farmers and not parched wildlife.

It is not about downstream rights, but PRIOR rights. Big difference. Out here in the west, our saying is:
Whiskey is for drinking, and water is for fighting.
Sadly, it seems like Texans and Easterners want to come here and pollute our water (which we have precious little of).
But all that MAY be changing. We, as individuals, have been prevented from capturing the runoff due to western water law. However, some lawyer and engineers have recently figured out that due to all concrete, farm lands, etc and our

According to http://www.nationalatlas.gov [nationalatlas.gov], the driest parts of Colorado get about 7" of rain annually (average rainfall is about 15"). that comes to 190,080 gallons per acre and would provide the total (drinking, washing, etc.) annual water usage (approximately 100 gallons per day per person, according to the US geological survey [usgs.gov]) of 5 people.

It's illegal because their water rights are based on a first come (excluding Indians) basis. Conventional wisdom (since disproven) was that collecting rainwater prevented it from going to it's rightful owners. More recent scientific studies have demonstrated that only 3% of rainwater ends up in the waterways.

Do you know why it's illegal to collect rainwater in a barrel in Utah and Colorado? If there is only a gallon of water in the air over an acre of land, removing a quart does in fact change the balance of things.

That's a load of pseudoscience, backing up a law that exists only for revenue, cronyism, and political control. If you store water off your roof or that falls from the sky, and then use it in your home or for irrigation, you're returning that water right back into the water table...in fact, use in the home returns it more effectively, because it is reintroduced a few feet under the soil by your septic system. You're not 'stealing' water- it doesn't go anywhere.

If you want to know the real reason laws like that exist, read The Milagro Beanfield War [wikipedia.org] (annoyingly, that link is about the movie, not the book.) I read it in middle school, and it gave me great insight into how big business pushes citizens around.

Also, you can take a look at what the Israelis are doing to all of the rivers that feed into or border Palestine for a great example of how water is controlled for racial oppression and political power.

Feel free to disprove this by doing a list of films about death row inmates and whether they are based on true events and whether that portrayal includes prior convictions.

Whether your premise is true or not, showing that such films exist would neither prove nor disprove it. You've made a connection in your head between fictionalized criminals and the motivations of movie makers but you've shown no actual proof for it, just a rationalization. Just as good a reason for such fictionalization is that the writers want to tell a specific story so they make it all up rather than go looking for some real person who fits the profile, after all it is fiction, not a documentary. The

Yes, and United Fruit were fine upstanding corporate citizens, since Gabriel Garcia Marquez wrote a magic realist novel set in a landscape of their abuses, and therefore it can't possibly be true.

The OP probably should have come out with a better, and nonfiction, reference (like Cadillac Desert), but your death row movie comparison is facile. One doesn't have to go far [wikipedia.org] to find examples of wrongfully-convicted death row inmates.

Only a gallon of water over an acre of land? I doubt it.
I'm not really used to the Imperial System, but I'll try my best to do the calculation in it.
1 acre = "how much a man with an ox can manage in 1 day"
1 gallon = "1 eights of a bushel"
1 bushel = "the volume of a pile of wheat which weighs 64 tower pounds"
1 tower pound = "5400 troy grains"
1 troy grain = "64.79891 milligrams"
1 quart = "a quarter of a gallon"
density of wheat = 950 000 karat / hogshead
average humidity in Colorado = 40%
assume a humidity of 40%, and you get about 40 gallons of water in the furlong of air over an acre of land. A quart doesn't really seem to make that much of a difference.

I don't think they'll be down to the level of a still suit for quite a few years yet. Equipment like the urine/water recycling system on the space station or the article's desert "dehumidifier" are bulky.

Plus we just don't have any real economic incentive for creating still suits -- we don't have a lot of people who want to live in the deep deserts.

All but the most barren deserts on this planet usually have a replenishing water supply somewhere. A pump, a cistern, and some plastic bottles is much easier to maintain (not to mention more comfortable) than a still suit will ever be.

It certainly would reduce the amount of humidity downwind. Luckily, downwind is where some poor bastard who isn't you lives. Handy, isn't it?

(In a less "caricature of a Fremen libertarian" vein, I imagine that this sort of tech, on a large scale, could indeed have unpleasant effects for those downwind of it. Looking at the stark difference in climate of otherwise similar regions, one in front of the big mountain range that blocks moist air, and the other behind it, is pretty much geography 101 stuff, the

How do they expect to keep such large structures safe from worms? I guess this is a typical melange bull market phenomenon. As soon as the price of spice jumps past $70 these people start building unsustainable castles in the sand. I for one will continue diligently keeping urinating into my stillsuit with the water recycling conservatively set on 'maximum.'

When I was 12 they taught us how to make a moisture trap with a can and some cellophane. Granted we weren't in a desert, but I am surprised if this "new" development surprises anybody.

Clearly, this is on a larger scale and far more impressive than what you did when you were 12.

Seriously, just because you did something which is conceptually similar, doesn't mean that this isn't an advance. Conceptually, flight hasn't changed since the Wright Brothers. Practically, it obviously has.

So in a decade when these are ubiquitous and most of the world is a desert, suddenly the Fraunhofer Institute will announce they had a patent on this and anyone drinking the water will have to pay licensing fees.

I don't think that desert-dwelling nomads today care much (or, indeed, are even aware of) the Fraunhofer Institute and the patents it hold. If, in a decaede, most of the world will indeed become a desert, I doubt anyone would care by that time. In fact, I doubt the institute would still exist...

The trick in TFA is pulling water out of the air without keeping parts of your apparatus below the dew point, which takes a fair bit of energy. There are still some active parts, looks like mostly pumps, and some solar heating; but no refrigeration is required.

If you have massive energy to throw at the problem, it is trivial(like a great many problems), solving it with relatively little energy is the real trick.

Here in California our snow packs are dwindling year after year, which means our valleys are likely to revert to their natural desert climate. That's where a full third of our nation's food comes from. We might want to consider some windtraps, not growing rice in a desert, or maybe borrow some Australian expertise to do something cool [youtube.com].

That does not necessarily mean that it should come from there forever. Just as the Rust Belt de-industrialized over decades, California could reduce the amount it farms. The employees can go back to Mexico and the owners can invest in something (or someplace) different.

The problem with this design is it requires electricity, which means expensive solar cells and periodic maintenance to clean them off.

The moisture traps mentioned in Dune already do exist, and are entirely passive. You need an underground chamber with a few vents in the sides, and vent in the top with a chimney. The air rises in the chimney creating a constant flow of air into the chamber, and moisture condenses due to the cooler conditions in the chamber than outside.

A system based on these principles wouldn't require energy in the form of electricity, despite the mention of photovoltaic cells. The energy needed to lift the brine to the collectors can be provided by the dilute solution leaving the collectors headed for the underground distillation section. More mass leaves the collectors than enters them, compensating for some energy lost to friction.
Given the effects of the salinity of the solution and the availability of solar energy for heat, I don't think the vacu

This method seems to result in pure distilled water which is generally considered harmful as your sole water supply. It's lacking in minerals that the body uses and also will turn acidic naturally. I guess since you're IN a desert though, they could scoop up a few spoonfuls of dirt and mix it in with your nice clear glass of fresh water.:-)

This method seems to result in pure distilled water which is generally considered harmful as your sole water supply. It's lacking in minerals that the body uses and also will turn acidic naturally.

I learned this in geology class, but apparently it's not universally accepted as true anymore. If you can find a reliable cite to support it, I'd be interested in reinstating my previous belief though.

I live in southeastern Australia, and down here, we haven't had regular rainfall now since 1995. Melbourne's water reserves are currently sitting at around 25%. The government's been talking about dredging the Yarra, the city's river, and that is only about a third of peak level at the moment as it is.

This tells me that the long term trend for Victoria is desertification. Queensland is getting floods these days, while we get barely a drop. Unless we're planning on abandoning the entire state, we're going to need technologies exactly like these, in order to be able to continue to live here.

When I read this article I was expecting to see another machine based on the ammonia absorption cycle. I was pleasantly surprised to see something new. This is interesting and should be followed to see if it becomes reality.

It's been possible to build an air-water condenser using the ammonia absorption cycle since the 1800s. Blow air across the cold outer surface and the heat exchange causes condensation. A gentleman proposed "oasis machines" which would be a condenser hidden in a decorative pool / fountain from which local villagers could draw water. It was self contained and needed no outside electricity, perhaps solar. He proposed it as a solution to providing water to villagers in Africa, etc. A poster above did mention the problem of the water lacking in mineral nutrients.

The caretaker of my building in Cairo directs the water that condenses in all of the air-conditioner units in the building into the gardens. While it isn't energy efficient AT ALL, I am always surprised by how much water gets to the garden. And as the weather gets hotter, the residents use their air-con more meaning more water for the garden. Again, it's not energy efficient in any way, but it does save water by reclaiming it from the air, and quite a lot of it.

Humidity is relative. A desert can have much more moisture in the air than a much colder, much more humid area. It's just that, at 50C degrees, the air can hold much more water than it can at 10C degrees. So the same amount of water that makes the desert 15% relative humidity, can result in rain (100% relative humidity) in colder climate.

It's the same thing that allows far more sugar/salt/jello/etc. to dissolve in warm water than cold...

Frank Herbert, while speaking in a radio interview on a call-in show around 1984, said that he saw a pilot project of a desert moisture collector while he was doing research as a journalist back in the Sixties.

If you want to get enough water to live out of that mug, I'd suggest you dig a pit, put the mug in the bottom of it, pile any vegetation you can get around the edges, piss in it for good measure, then secure your ground sheet over the top with rocks and use a pebble to make it slanted towards the middle. Actually produces quite a lot of water, you might want to use a cooking pot instead.

I'm no expert but a thing to be aware of, it won't produce pure water. It will produce other liquids/chemicals that condense at vaguely similar temperatures that happen to be vapour in there.

If you haven't been eating or drinking anything terribly bad, using pee shouldn't be too bad, but be a bit selective with the vegetation - skip it if it's got the usual "Nature's warning colours" all over it, or smells funny.

Various other alcohols (including nasty ones) have boiling points not far below that of water.

Yes been done in South America for some time http://www.oas.org/dsd/publications/Unit/oea59e/ch12.htm [oas.org]
"Fog harvesting has been investigated for more than thirty years and has been implemented successfully in the mountainous coastal areas of Chile (see case study in Part C, Chapter 5), Ecuador, Mexico, and Peru."

Most (All, before Dias discovered Cape in 1488) of the goods carried from India and China to Europe. How did you think Chinese sold lowest quality (according to their standards) of earth-ware to your ancestors as "finest in the world" for centuries?

Actually it's very simple you have a flat sheet of plastic or waterproof material, then hang it up so that one corner is sloping down to some sort of collection media (ie a bottle) and then wait for the hopefully cool night. During the night the material will be cooler than the dew point of the air causing moisture to condense on the material. Once condensed the water will slowly flow down to the collection point. Normally you won't get much water but in some situations the amount collected could be the dif

Hell with the 'white', when 'man' discovers it it's important. Mankind pat itself on the back whenever they figure out how to do something (no matter how poorly) that nature figured out a long time ago. I often think of going back in time and telling the Arabi who invented the magnetic compass - 'hey you know salmon have these in their brain at birth'. He'd be all like "! "

Can you give citations for dessert dwellers using brine solutions and vacuum chambers to pull water out of the air in the absence of any material with a temperature below the due point? I won't hold you to the 'thousands of years' part. Last I checked, dessert dwellers didn't do so well with salt water until recently, and then, only industrial scale desalinization projects. If they were using this method, it seems like they should have hit on desalinization a very long time ago.

Or did you not RTFA and thus think it was the trivial survival technique using condensation and gravity during night time hours?

Given the state of scientific knowledge in 1965 (when dune was published) it's a lot harder SF than some people seem to realise.Herbert did some serious background research for Dune IMO.

Sure bits of it seem *now* to us as absurd as Doc Smith's diesel-engined spacecraft, but in 1965, 12 years after the discover of DNA, 17 years after the initial formalisation of classical information theory, when computers were still mostly small-room-sized, the idea the genetic code could pass down memories wasn't all that outlandish a hypothesis - in fact it seemed pretty reasonable. If you were writing now you'd probably come up with people being genetically engineered to add informational appendicies to germ line DNA rather than the ability being built-in by evolution, but there's nothing impossible about it. And if you pay attention to the books, you'll note that being able to "see the future" doesn't work in a naive way either, it's clearly been modelled on "quantum collapse" and "many fingered time" that any passing 1960s physicists would have talked the ear off Herbert about.

And with very powerful figures *right now* calling for the Death of the Internet, is a ban on computing devices really that outlandish? Sure, the chances of them winning are slim in practice, but still.

Sadly, Niven didn't grow out of the Protector crapola. I love Neutron Star and a lot of the other early Known Universe stories, but the Protectors-are-human-ancestors-from-another-planet theme sounded moronic even forty years ago.

IMO, the dividing line is the amount of hand-waving you do. Like how to survive in the desert:

Hard fantasy: "I cast a spell of protection from elements"Soft fantasy: "The quantronic radiation on this planet..."Soft SF: "I'll put on my stillsuit"Hard SF: Even more science?

I sometimes get the impression that SF defines themselves too narrow because SF is still supposed to tell a story which is what should engage you, it's not a discovery show on what science could be like 100 years from now. Of course, if science has no real place at all it's really a space opera but it doesn't have to be primarily a science story as long as the storyline is interrelated with the science.

There was a lovely old story by Issac Asimov - can't remember the name, sorry, and any search of his work will be a long walk - that told of the author of Genesis trying to write about the Big Bang in terms of particle physics. His son chastised him over the amount of writing materials that would take. At the end of the dialogue it was oversimplified to "(sigh) In the beginning..."

Fantasy is a good way to simplify scientific concepts, provided the fantasy actually tracks the science. If there's no believability, it doesn't make a very good story.

The line between SF and Fantasy has always been a little blurry (nowhere near as blurry as in Chalker's "Masters of Flux and Anchor" series which was a brilliant expansion on Clarke's Law, and a very good read if you can ignore the implicit mysogny in most of his works).

I've worried that Clarke's Law is taken as transitive by some (thank The Pasta for predictable and reproduceable results). I've also thought that we're on a trend to realisation of C.P.Snow's great cultural divide between the knowledge "haves" and "have-nots". I see this among friends who firmly believe that technology comes from observing certain rituals, rather than scientific advancement and engineering process. They're very Cargo Cult and not a little bit frightening.

The truly frightening thing is I have difficulty explaining the difference to them. The gulf is almost too deep to cross now.

There are fantasy elements, though they're framed (at least in the later books) in a sort of pseudo-scientific sense. But the ecological aspects of Dune, well those are based on a lot sounder principles. This was Herbert's particular area of expertise, and he put a considerable amount of effort into developing the ecology and climate of Arrakis, and the Fremen technology, while certainly more advanced than ours, isn't so advanced that I wouldn't be surprised if it were possible within a few decades.

I've often thought that equatorial regions near oceans are letting a huge energy resource go to waste while they suffer increased desertification.

Sun light could be used to pump sea water, evaporate it, and pump condensed briny water back to the sea. You could also use solar powered RO, but that might be more expensive due to the media replacement needs.

Even if you did not get enough for western style irrigation you could use it to slow down or reverse the process of desertification, preserving marginal ad

Good for you, except it isn't trolling/., its still trolling/b/ except now where no one from/b/ will ever read it. I'm pretty sure all their trolls are scripted by now, and generally are at least amusing, or... you know... someone in the flavor of trolling the average/. user.

I'd personally take the "did you hear about the singularity" guy, or the iPhone rectal stimulation guy, it at least is somewhat in the scope of/.